.75 cubic feet .75 cubic feet represents three-quarters of a cubic foot, a measurement commonly used in shipping to calculate dimensional weight. To determine if your package fits within .75 cubic feet, multiply length × width × height in inches and divide by 1,728. Dimensional weight may affect your shipping rate more than actual weight, especially with carriers like FedEx or USPS. Optimizing your packaging size to stay under specific volume thresholds can result in significant cost savings.